/*-------------------------------------------------------------------------
 *
 * pg_largeobject.h
 *	  "大对象" 系统目录 (pg_largeobject) 的定义
 *
 *
 * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/catalog/pg_largeobject.h
 *
 * NOTES
 *	  Catalog.pm 模块读取此文件并推导模式
 *	  信息。
 *
 *-------------------------------------------------------------------------
 */
#ifndef PG_LARGEOBJECT_H
#define PG_LARGEOBJECT_H

#include "catalog/genbki.h"
#include "catalog/pg_largeobject_d.h"

/* ----------------
 *		pg_largeobject定义。cpp将其转换为
 *		typedef struct FormData_pg_largeobject
 * ----------------
 */
CATALOG(pg_largeobject,2613,LargeObjectRelationId)
{
	Oid			loid BKI_LOOKUP(pg_largeobject_metadata);	/* 大对象的标识符 */
	int32		pageno;			/* 页码（从0开始） */

	/* 数据可变长度，但我们允许直接访问；见inv_api.c */
	bytea		data BKI_FORCE_NOT_NULL;	/* 页面的数据（可能是
 *	零长度） */
} FormData_pg_largeobject;

/* ----------------
 *		Form_pg_largeobject对应于具有
 *		pg_largeobject关系格式的元组的指针。
 * ----------------
 */
typedef FormData_pg_largeobject *Form_pg_largeobject;

DECLARE_UNIQUE_INDEX_PKEY(pg_largeobject_loid_pn_index, 2683, LargeObjectLOidPNIndexId, on pg_largeobject using btree(loid oid_ops, pageno int4_ops));

extern Oid	LargeObjectCreate(Oid loid);
extern void LargeObjectDrop(Oid loid);
extern bool LargeObjectExists(Oid loid);

#endif							/* PG_LARGEOBJECT_H */
